November 17, 1916] 



SCIENCE 



719 



time that the streamers in the southern as well 

 as the northern sky appeared to meet a con- 

 siderable number of degrees to the southeast 

 of the zenith, but the exact location was not 

 observed. One fact of similarity between 

 these two appearances of the aurora in the 

 southern sky was that in both cases the stream- 

 ers appeared in the southern half of the 

 heavens before any indication of an aurora 

 showed in the north; as if some condition of 

 the atmosphere susceptible to an auroral dis- 

 play had been reached to the south before it 

 has been reached to the north of the point of 

 observation, indicating some progressive 

 change in the atmosphere from south to 

 north. 



the heavens could apparently be located within 

 an area of the size of the full moon, which has 

 an angular diameter of about one half degree. 



Professor Nutting, describing the aurora in 

 his article in Science, states that the " focus 

 of the spectacle was the zenith itself." So it 

 might appear with a casual glance, being near 

 the zenith, and with nothing to mark that 

 point. His paper is mainly concerned with 

 other features of the display and is an excel- 

 lent description of them, but the position 

 among the stars toward which the streamers 

 converged was evidently not noted. 



The place of observation where the aurora 

 was observed by the writer was about four- 

 teen miles north of Charlottetown, Prince 



Fig. 2. Auroral corona forming a luminous band across the sky passing through the focus as 

 observed about 8:25 p.m. 



THE FOCUS OP THE STREAMERS 



The position of the apparent focus of the 

 streamers near the zenith is of special impor- 

 tance owing to the relation of the direction of 

 the streamers to the direction of the lines of 

 force of the magnetic field of the earth. The 

 point of focus was located about two degrees 

 south of the star 7 Lyra at 8:20 o'clock At- 

 lantic time. The time was later verified 

 through the local telegraph office. The spot in 



Edward Island, which is at latitude 46° 13' 

 58.48", longitude 63° T 23.64" according to 

 values provided by the Department of Mines, 

 Canada. The latitude of the place of observa- 

 tion is taken as 46° 26' and longitude as 

 63° 8'. Mr. C. S. Brainin, of Columbia Uni- 

 versity, has kindly computed the position of 

 the zenith with respect to the stars at the time 

 of observation, which gives that point as 

 shown in Pig. 1. The zenith distance of the 



